Fix leading spaces in kubectl commands

This is causing bash/zsh shells to not to record the executed command in the
history. See this link for details: https://unix.stackexchange.com/questions/115917/why-is-bash-not-storing-commands-that-start-with-spaces

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

docs/tasks/configure-pod-container/assign-pods-nodes.md

@@ -19,7 +19,7 @@ Kubernetes cluster.
 
 1. List the nodes in your cluster:
 
-        kubectl get nodes
+       kubectl get nodes
 
     The output is similar to this:
 
@@ -30,13 +30,13 @@ Kubernetes cluster.
 
 1. Chose one of your nodes, and add a label to it:
 
-        kubectl label nodes <your-node-name> disktype=ssd
+       kubectl label nodes <your-node-name> disktype=ssd
 
     where `<your-node-name>` is the name of your chosen node.
 
 1. Verify that your chosen node has a `disktype=ssd` label:
 
-        kubectl get nodes --show-labels
+       kubectl get nodes --show-labels
 
 
     The output is similar to this:
@@ -60,11 +60,11 @@ a `disktype=ssd` label.
 1. Use the configuration file to create a pod that will get scheduled on your
    chosen node:
 
-        kubectl create -f https://k8s.io/docs/tasks/configure-pod-container/pod.yaml
+       kubectl create -f https://k8s.io/docs/tasks/configure-pod-container/pod.yaml
 
 1. Verify that the pod is running on your chosen node:
 
-        kubectl get pods --output=wide
+       kubectl get pods --output=wide
 
     The output is similar to this: